A radio remote unit (RRU) in a digital indoor distributed system in a live network includes 2×2 antennas, that is, includes two transmit antennas and two receive antennas. In an indoor scenario, when leveling spatial isolation is relatively low, an overlapping area (referred to as a “cell joint area” below) between different RRUs is relatively large. In addition, indoor space is relatively enclosed, and therefore the cell joint area is subject to less external interference, and a signal to interference plus noise ratio is high and correlation is low in the overlapping area. In this case, a relatively high three-stream multiplexing/four-stream multiplexing ratio can be obtained.
In a current digital indoor distributed system network, when a quantity of RRUs is not increased, different logical port numbers may be configured for antenna ports of two RRUs that have an overlapping coverage area, so that a four-receive antenna (4R) terminal in a joint area between the two RRUs supports 4×4 virtual multiple-input multiple-output (MIMO), thereby increasing a spatial multiplexing gain of the 4R terminal, and obtaining a higher data transfer rate.
However, when a plurality of RRUs coexist, a problem to be resolved urgently is how to configure antenna ports for each RRU to enable the terminal to more easily enter, when moving in coverage areas of the plurality of RRUs, a cell joint area in which the terminal supports 4×4 virtual MIMO.